Oilfield operations may be performed in order to extract fluids from the earth. When a well site is completed, pressure control equipment may be placed near the surface of the earth. The pressure control equipment may control the pressure in the wellbore while drilling, completing and producing the wellbore. The pressure control equipment may include blowout preventers (BOP), rotating control devices, and the like.
The rotating control device or RCD is a drill-through device with a rotating seal that contacts and seals against the drill string (drill pipe with tool joints, casing, drill collars, Kelly, etc.) for the purposes of controlling the pressure or fluid flow to the surface. For reference to an existing description of a rotating control device, please see US patent publication number 2009/0139724 entitled “Latch Position Indicator System and Method”, US patent publication number 2011/0024195 entitled “Drilling with a High Pressure RCD”, US patent publication number 2011/0315404 entitled “Lubricating Seal for use with a Tubular”, U.S. Pat. No. 8,100,189, U.S. Pat. No. 8,066,062, U.S. Pat. No. 7,240,727, U.S. Pat. No. 7,237,618, U.S. Pat. No. 7,174,956, U.S. Pat. No. 5,647,444, U.S. Pat. No. 5,662,181, and U.S. Pat. No. 5,901,964 the disclosures of which are hereby incorporated by reference. The seals in the RCD are typically constructed of elastomer material and have a tendency to wear with usage. The higher the differential pressures across the annular seal, the more rapid the wear rate. Further, the seals tend to invert during pull out from the RCD, a drilling operation referred to as “stripping out”. The seal may invert by bending inward and folding into itself. When the seal inverts it may fail to seal the wellbore annulus and need to be replaced. In high pressure, and/or high temperature wells the need is greater for a more robust and efficient seal to extend its useful life. In some applications or functions of a seal, a need exists to increase lubricity and consequently reduce frictional heat which accelerates elastomer wear. In others, a need exists to enhance the seal's stretch tightness on the drill string, thus assuring the transfer of torque required to rotate the inner race of the RCD's bearing assembly in harmony with components of the drill string being sealed against.
A need exists for an improved annular seal having increased endurance, toughness, and/or permanence in an RCD.